Indus River Delta

About the Area

Originating at Lake Ngangla Ringco, high on the Tibetan Plateau, the Indus flows more than 3,000km, creating a wide delta of swamps, streams, and extensive mangroves before bursting into the Arabian Sea.

For much of its course, the river is a wide channel of cloudy water, providing mineral-rich soil and water to its floodplains. The Indus River Delta consists of clay and other infertile soils, and is very swampy. It is an important region for migrating water birds, and is an area rich in freshwater fauna. The delta receives between 25 and 50cm (10-20in) of rain in a normal year. Average temperatures for the delta region in July are 70-85°F and 50-70°F in January.

It is home to one of the few species of freshwater dolphin worldwide, the Indus River dolphin (Platanista minor) and numerous species of distinctive fish, many of which live in or migrate through the waters of the Indus River Delta.

Important food species like large freshwater shrimp (Macrobrachium spp.) are part of the abundant aquatic life of the delta.

Size:
40,000 sq. km (16,000 sq. miles)

Habitat type:
Large River Deltas

Geographic Location:
Western part of the Indian subcontinent: Pakistan

Conservation Status:Critical/Endangered

Local Species
In addition to Indus River dolphin, the river is home to a number of endemic fish, including Indus baril (Barilius modestus), Indus garua (Clupisoma naziri) and Rita catfish (Rita rita).

Several snakehead fishes also live here, including giant snakehead (Channa marulius), which can grow to be 2m (6ft) long and eats fish, frogs, snakes, insects, and earthworms. There are even reports that it will occasionally eat a water bird!

The Hilsa shad (Tenualosa ilisha) swims up from the Arabian Sea to spawn in freshwater. This fast swimmer has been clocked covering 71km per day.

Featured species

The Indus River dolphin is one of the world's rarest mammals and most endangered cetaceans. Only about 1,000 of this unique species exist today in the lower reaches of the Indus River. It has a long beak and a stocky body. It has a low triangular hump on its back in place of a 'true' dorsal fin. It is gray-brown in color, sometimes with a pinkish belly. It measures between 1.5 and 2.5m (5-8ft) in length and weighs 80-90 kg.

The Indus River dolphin is functionally blind having evolved without a crystalline lens or well-developed light-sensitive organ. However, this is not a disadvantage but an adaptation to living in the silt-laden turbid waters of the Indus where eyes are virtually useless, as very little light penetrates below the surface of the murky water.

This dolphin swims on its side, at times enabling it to swim in water as shallow as 30cm. As it swims on its side, it trails a flipper along the bottom of the river. After 30 to 60 seconds, when it needs to breath, it swims to the surface, rotates upright to take in the air, and then rotates thorough 90 degrees again as it swims back to the bottom.

Numbers have dramatically declined since the construction of the irrigation system in the Indus. Most now remain in a 1,200km stretch of the Indus River.

Threats
Dams on the river reduce flows in lower portions of the system and limit the transport of fertile sediments downstream into the delta. They also pose a serious threat to the survival of the Indus River dolphin, as the remaining dolphins become isolated into smaller groups.

Water extraction for irrigation, runoff of chemicals into the rivers, and introduced species also threaten the freshwater species of the delta.

WWF is developing a long-term conservation programme, ranging up to 50 years, focusing on freshwater scarcity in the coastal areas of the Indus delta.

WWF also works to conserve the endangered Indus River dolphin. In addition to efforts to conserve their habitat, including addressing problems such as river pollution, WWF staff have also been involved in rescue mission when individual dolphins found themselves trapped in canals.